Is pregnant cows' milk really a health threat?

by Maggie Seiler, Associate Editor

A human health concern accuses milk from pregnant cows, which is customarily high in estrogens, of affecting blood estrogen levels in humans. High levels of that hormone in the human bloodstream have been linked to cancers and male reproductive disorders.

So can milk really be to blame for these frightening human conditions?

Researchers in Slovenia would say no.

The results of a recent study conducted there indicated adult mice that received milk from pregnant cows showed no difference in blood estrogen levels, weight of reproductive organs, nor were the males more likely to have low testosterone concentrations.

The same held true when the scientists added 10 times the concentration of estrogens of pregnant cows to milk fed to the mice. In fact, the researchers had to add more than 1,000 times the typical pregnant cow's estrogen levels in order to see a difference.

This estrogen-laden milk that contained more than 1,000 times the normal hormone level elevated plasma estrogens in both male and female mice, lowered testosterone levels in males, and increased reproductive organ weights. Fortunately, this more toxic hormone level would not occur naturally in cows' milk.

The researchers went on to explain that many animal and human metabolic processes, such as those that happen in the liver, naturally filter estrogens before they reach the bloodstream.

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August 8, 2016
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